1. Field of the Invention
The invention relates generally to configuration management of a storage system. Particularly, the invention relates to management of storage areas at the time of backups.
2. Description of Related Art
Companies back up data as a means of precaution against failures of storage apparatuses, data destruction by computer viruses, and data loss due to users' incorrect operation. One of backup techniques is a method of using a storage copy function capable of curbing the influence on a host computer on which an application operates. When performing a backup, data written to a storage area of a storage apparatus which stores data used by the application (primary volume; hereinafter referred to as “PVOL”) is copied to another storage area (secondary volume; hereinafter referred to as “SVOL”). Japanese Patent Laid-Open (Kokai) Application Publication No. 2004-164318 discloses split operation to cancel the copy state between the PVOL and the SVOL except when a designated backup is performed. The split operation is to manage differential data with a data change in the PVOL by stopping the copy function during the operation of the relevant application. After the task is completed, the application is stopped and the differential data is copied from the PVOL to the SVOL. This is because, if a backup is performed during the task, the load will be imposed on the PVOL, thereby degrading the storage performance.
Recently, a thin provisioning technique is used as a technique for efficiently utilizing the capacity of media in a storage system. This technique is to provide virtual volumes, which are virtual storage areas, to a computer and allocate a physical storage area only to an area for which a write request is made from among the virtual storage areas. Furthermore, U.S. Pat. No. 7,613,945 discloses a method for migrating data on a page basis, each page being a smaller segment than a volume, according to I/O (Input/Output) access frequency form a host computer. This technique can manage a plurality of types of media as a pool and migrate a high-access-frequency page to a high-speed medium and a low-access-frequency page to a low-speed medium.